This project provides techniques to improve hot-mix asphalt (HMA) overlays specifically through the use of
special additives and innovative surfacing technologies with aggregates that are locally available in Illinois. The
ultimate goal is to improve pavement performance through optimized materials while also controlling cost by
efficiently using local materials. Therefore, the proposed new mixes use locally available aggregates when
possible. The project also considered the use of alternative aggregates such as steel slag to increase the
friction quality of the HMA and therefore improve pavement performance. To evaluate the newly developed
wearing course mixtures and evaluate their performance under actual traffic loading, test pavements were
constructed, including control mixtures, between August and November 2010 in northern Illinois. The newly
proposed mixtures include fine dense-graded HMA and stone matrix asphalt (SMA). The fine dense-graded
HMA was designed using the Bailey method and developed with the hope of improved compactability for thinner
asphalt layers. The SMA contained a 4.75-mm nominal maximum aggregate size (NMAS) that allows for layers
as thin as 0.75 in. On-site performance tests were conducted at 4-month intervals following construction; the
tests include noise, friction, rutting, and texture profiling. An engineering benefit analysis was performed to
evaluate the new mixes’ cost effectiveness. New HMAs are proposed, along with alternative cross-sections that
improve pavement performance while controlling costs.